Electron paramagnetic resonance without vortex noise in superconducting Gd doped YBaCuO

Abstract An electron spin resonance spectrometer is described in which noise generated by superconducting vortex motion is avoided, The efficacity of the method is demonstrated by the low temperature EPR of Gd doped YBa 2 (Cu 0.98 Co 0.02 ) 3 with T c ≈ 92 K.